In a welding apparatus as an example of conventional electric equipment, a dedicated input/output circuit performs the input from the outside of the welding apparatus or the output to the outside (for example, Unexamined Japanese Patent Publication No. H04-17977). The input/output function is restricted and has no flexibility, and addition or modification of a circuit is required in order to alter the function of the welding apparatus.
FIG. 12 shows a configuration example of conventional welding apparatuses. FIG. 12 describes only a section for receiving information from the outside, and omits a configuration such as a welding output section that is required for arc welding.
Hereinafter, the welding apparatus of FIG. 12 is described. Only the input operation is described and drawn.
As shown in FIG. 12, welding apparatus 101 includes sequence control circuit 103. An on-off signal of trigger switch 102 is input to sequence control circuit 103 via wire feeder 105 having wire feeding motor 106. Welding apparatus 101 thus recognizes the state of trigger switch 102. Generally, welding apparatus 101 includes several input sections for receiving such a signal or the like. Similarly, welding apparatus 101 includes several output sections for outputting a signal or the like. Sequence control circuit 103 controls the wire feeding motor of wire feeder 105 via wire-feed control circuit 104.
Each of the above-mentioned input sections is dedicated to each function. Signals from trigger switch 102, for example, are input to sequence control circuit 103. In other words, the signals are input to the other circuit only when the connection is changed.
When the welding apparatus is applied to a production line of a factory, it is required that various input signals are transmitted to the welding apparatus to control the operation. In order to make a worker in the outside know the operation of the welding apparatus, various signals need to be output from the welding apparatus to the outside.
However, the external input/output section of the conventional welding apparatus is formed of dedicated input/output circuits. A case where the indication of an input on-off signal is intended to be inverted is taken as an example. Each circuit is designed dedicatedly, so that the circuit is difficult to be modified. A new device for inverting the indication of the on-off signal needs to be disposed in the outside. Also for the output, each circuit is designed dedicatedly, so that a new device for inverting the indication of the on-off signal needs to be disposed in the outside.
Also when the phenomenon having occurred in the welding apparatus is intended to be obtained as a plurality of outputs, a new device needs to be disposed in the outside. Also when a plurality of phenomena having occurred in the outside is made to undergo a logical operation and the result of the logical operation is intended to be input as an input signal, a new device needs to be disposed in the outside or the wiring needs to be modified.
Therefore, whenever a production line is newly constructed or modified, a new device for external input/output needs to be introduced.